Smart Transducer Interface Standard - IEEE 1451 September 24, 2002Sensors Expo, Boston1 Proposed Changes to the Current IEEE 1451 Overall Architecture

September 24, 2002

Sensors Expo, Boston 1

Smart Transducer Interface Standard - IEEE 1451

Proposed Changes to the Current IEEE 1451 Overall Architecture

Robert N. Johnson

Telemonitor, Inc.

[email protected]

September 24, 2002

September 24, 2002



Outline

Review goals of IEEE 1451 Background Situation What should we standardize? Proposed “dot zero” standard Expected results Next Steps

September 24, 2002



Main goals for IEEE 1451

Develop network independent and vendor independent transducer interfaces.

Allow transducers to be replaced and/or moved with minimum effort.

Eliminate error prone, manual system configuration steps. Support a general transducer data, control, timing,

configuration and calibration model. Develop Transducer Electronic Data Sheets that remain

together with the transducer during normal operation.

September 24, 2002



First the Earth cooled...

1994--First “Smart Sensor Interface Standards Workshop” held at NIST resulting in study group for standard

1995--Study group forms two working groups: P1451.1 for the network processor model and P1451.2 for the transducer to microprocessor interface

1997--IEEE 1451.2-1997 is approved. P1451.3 and P1451.4 working groups agree to maintain major IEEE 1451 family traits

2001--IEEE P1451.5 study group starts work on a standard for wireless sensor

2002--Proposals made to coordinate the TEDS and operational models of the family of IEEE P1451 standards to improve compatibility and reduce duplication of effort

September 24, 2002



1997 Architecture Guidelines

Interfaces are defined, not modules Modules may support multiple interfaces

Higher-level standards must be maintained At that time this meant providing a way to generate a

1451.2 TEDS Partitioning is invisible beyond the immediate interface

A module or network device should not have to know or care what interfaces are implemented past the immediate one

Hot swaps must be allowed and passed on Each standard must support a way to simulate the “hot

swap” of a transducer and force the network-side device to accept the updated TEDS

September 24, 2002



Present Situation

The IEEE 1451 family of standards has established several valuable basic principles of smart transducers, the most important of which is the TEDS

Different physical interfaces are needed by different applications, and more will be needed in the future.

Unless guidance and coordination is provided, we will duplicate efforts and end up with incompatible devices in the standards family.

Now is the time to address this issue; IEEE 1451.1 and 1451.2 are up for revision and renewal, and the proposed standards P1451.3, P1451.4, and P1451.5 are not yet approved.

September 24, 2002



Core Values of the IEEE 1451 Family

Extensible Transducer Electronic Data Sheet (TEDS) General calibration/correction model for transducers Data models based on common standards such as IEEE

floating point numbers Physical units representation based on SI units Control and operation models for different kinds of

transducers Flexible correction engine concept All of the above must be common in order to have a basis

for a common TEDS

September 24, 2002



Power of TEDS plus correction engine

Data Channels

No. Property Type Units Minimum Maximum1 Temperature Sensor K 233.15 (-40° C) 358.15 (85° C)2 Roll Zero Actuator radians -1.57 (-90°) 1.57 (90°)3 Pitch Zero Actuator radians -1.57 (-90°) 1.57 (90°)4 Roll Zero Sensor radians -1.57 (-90°) 1.57 (90°)5 Pitch Zero Sensor radians -1.57 (-90°) 1.57 (90°)6 X Acceleration Sensor m/s2 -19.6 (-2 g) 19.6 (2 g)7 Y Acceleration Sensor m/s2 -19.6 (-2 g) 19.6 (2 g)8 Roll (about X) Sensor radians -1.31 (-75°) 1.31 (75°)9 Pitch (about Y) Sensor radians -1.31 (-75°) 1.31 (75°)

Multi-channel acceleration/tilt sensor:• Hardware channels for temperature and acceleration• Correction engine performs temperature compensation• Virtual actuators for zero correction• Virtual sensors for tilt (roll and pitch)• Correction engine converts to angle• Number order of channels is important

September 24, 2002



It’s the TEDS…!

Industry Extension TEDS


Meta-TEDS (mandatory)


End Users’ Application specific TEDS

Meta-ID TEDS

Machine readable Human readable Application specific

Future extensions

Channel TEDS (mandatory)

Calibration TEDS

Channel ID TEDS

Calibration ID TEDS

September 24, 2002



Partition the TEDS

New Meta TEDS

New Channel TEDS

Move physical interface related fields

New Physical Interface Meta TEDS

New Physical Interface Channel TEDS

Meta-ID TEDS

Channel-ID TEDSOther TEDS blocks can remain the same.

Supports use of different physical layers....

September 24, 2002



Proposed IEEE P1451.0 TEDS Architecture



Meta-TEDS (mandatory)


End Users’ Application specific TEDS

Meta-ID TEDS

Machine readable Human readable Application specific

Future extensions

Channel TEDS (mandatory)

Calibration TEDS

Channel ID TEDS

Calibration ID TEDS

Physical layer Meta-TEDS(Dot-X specific)

Physical layer Channel-TEDS(Dot-X specific)

Everything not “Dot-X specific” is defined in IEEE P1451.0

September 24, 2002



What About IEEE P1451.4?

The compact TEDS proposed for IEEE P1451.4 cannot include a complete IEEE P1451.0 TEDS, although a template file can provide most of the content

Also, since the data for a P1451.4 device is analog, a lot of the TEDS content is not applicable

BUT, the module that the P1451.4 device connects to can provide the translation to the full P1451.0 content in addition to the conversion between digital and analog

The important thing is that we coordinate such things as units, data representation, correction engine, etc. for true family compatibility

Properly done, other network-side devices need not know if the transducer is P1451.4 or another flavor

September 24, 2002



Results of IEEE P1451.0

Reduction in duplication of effort Commonality and compatibility cross the entire IEEE 1451

family of standards Common network-side view of all devices Ease of adding additional physical media when they are

needed in the future The proposed IEEE P1451.0 standardizes the message,

not the medium

September 24, 2002



What Next?

Form an IEEE P1451.0 study group Coordinate common elements with chairs of all the existing

working groups Review existing and proposed dot-x standards for impact Submit a Project Authorization Request to IEEE and form a

working group Write a draft standard We need to act quickly and your input and participation can

help

September 24, 2002



Questions/Comments?

Documents

Smart Transducer Interface Standard - IEEE 1451 September 24, 2002Sensors Expo, Boston1 Proposed Changes to the Current IEEE 1451 Overall Architecture